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Compact Laser Diode Drivers with TECs and Mounts for TO Can Pigtailed LDs
B, C, and H Pin Codes
A, D, E, and G Pin Codes
Main Operation Panel in Constant Power
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The CLD1010LP shown with the thermal protective cover installed.
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A pigtailed laser diode shown mounted in the CLD1010LP.
Thorlabs' Compact Laser Diode and Temperature Controllers are complete driver packages designed to drive and cool TO can fiber-coupled laser diodes. The CLD1010LP controller is compatible with A, D, E, and G pin configurations, while the CLD1011LP controller is compatible with B, C, and H pin configurations (see the Pin Diagrams tab for details). These all-in-one units supply up to 1.0 A of drive current, maintain the diode temperature with 0.005 °C of stability over 24 hours, provide a high degree of output stability, and prolong the life of the diode. The controllers also contain a built-in mount for portability and mechanical stability. In additional to a full complement of safety features, such as a soft-start mode, current and temperature limits, and external interlock compatibility, the CLD1010LP and CLD1011LP controllers both include a switchable noise reduction filter and a modulation input. They also each feature an RF Bias-T that allows the laser to be modulated between 200 kHz and 1 GHz with an external RF source (dependent on the specifications of your laser diode). These controllers can be operated in constant current or constant power mode; however, only laser diodes that include a monitor photodiode (pin codes A, B, C, and D) are compatible with constant power mode.
The devices are controlled with built-in 4.3" diagonal, color resistive touch screens, making it easy to tune, tweak, and optimize the laser output parameters. Operating parameters are set using the intuitive menu system, and the user is never more than two taps away from the home screen. A resistive touch screen allows for the screen to be operated when using gloves or other protective equipment. For screenshots of the interface, please see the Display tab. In addition to the touch screen controls, a mini-USB interface on the rear of the unit enables remote control of all settings using several common programming languages, including LabVIEW and the Standard Commands for Programmable Instruments (SCPI) standard. For the full array of options, please refer to the Software tab. When using the CLD1010LP or CLD1011LP to drive a laser, make sure that all of the operating parameters are set within the maximum ratings of your device.
When fully assembled, these compact devices measure just 4.37" x 2.9" x 6.69" (111 mm x 73.5 mm x 169.9 mm), ideal for tightly packed setups. Fiber cables can be fed through the ports on the back of the unit, which are also compatible with Thorlabs' FC-to-FC Mating Sleeves (not included). Two of the holes accept square flange mating sleeves, and two are designed for D-hole mating sleeves. A magnetically sealed lid encloses the laser package in the unit, protecting it from particulates and other lab hazards. A smaller cover that provides thermal protection from the environment can be installed independently of the magnetic lid (see the photo to the right). Two mounting clips, compatible with 1/4"-20 and M6 bolts, are supplied with each laser diode driver to secure it to a breadboard.
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These drivers are shipped with a power supply.
Thorlabs manufactures customized, application-specific butterfly mounts for OEM customers. Please see the OEM Modules tab for details.
Before operating any laser diode with these controllers, please check to ensure that the operating voltage of the intended diode does not exceed the compliance voltage of the controller.
For driver software, as well as programming reference guides for the Programmable Instruments (SCPI) standard, LabVIEW™, Visual C++, Visual C#, and Visual Basic, please see the Software tab.
Note: These laser diode drivers may be controlled locally via a touch screen or remotely over USB. When controlled locally via the touch screen, the resolution of the laser diode driver is limited by the display; the full resolution can be accessed when the device is controlled remotely. The command sets that are accessible over USB - for example, via LabVIEW or the Standard Commands for Programmable Instruments (SCPI) - offer increased resolution, as shown in the table below.
CLD1010LP and CLD1011LP Laser Diode Driver Specifications
CLD1010LP and CLD1011LP TEC Specifications
The interface for these laser diode controllers consists of a flat menu hierarchy that makes it easy to find parameters to adjust.
TO Can Diodes Compatible with the CLD1010LP
The CLD1010LP Laser Diode Driver and Temperature Controller is compatible with pigtailed TO Can laser diodes that have an A, D, E, or G pin code. Please use the pin diagrams below to classify your specific laser diode package and verify CLD1010LP compatibility. Details on the correct orientation for installing each pin code can be found in the manual. Please note that only laser diodes with pin codes that include a photodiode can be operated in constant power mode.
TO Can Diodes Compatible with the CLD1011LP
The CLD1011LP Laser Diode Driver and Temperature Controller is compatible with pigtailed TO Can laser diodes that have a B, C, or H pin code. Please use the pin diagrams below to classify your specific laser diode package and verify CLD1011LP compatibility. Details on the correct orientation for installing each pin code can be found in the manual. Please note that only laser diodes with pin codes that include a photodiode can be operated in constant power mode.
Software for Laser Diode Controllers
The download button below links to VISA VXI pnp™, MS Visual Studio™, MS Visual Studio.net™, LabVIEW™, and LabWindows/CVI™ drivers, firmware, utilities, and support documentation for Thorlabs' ITC4000 Series laser controllers, LDC4000 Series laser controllers, CLD1000 Series compact laser diode controllers, and TED4000 Series TEC controllers.
The software download page also offers programming reference notes for interfacing with compatible controllers using SCPI, LabVIEW, Visual C++, Visual C#, and Visual Basic. Please see the Programming Reference tab on the software download page for more information and download links.
The software packages support LabVIEW 8.5 and higher. If you are using an earlier version of LabVIEW, please contact Technical Support for assistance.
The PID circuit is often utilized as a control loop feedback controller and is very commonly used for many forms of servo circuits. The letters making up the acronym PID correspond to Proportional (P), Integral (I), and Derivative (D), which represents the three control settings of a PID circuit. The purpose of any servo circuit is to hold the system at a predetermined value (set point) for long periods of time. The PID circuit actively controls the system so as to hold it at the set point by generating an error signal that is essentially the difference between the set point and the current value. The three controls relate to the time-dependent error signal; at its simplest, this can be thought of as follows: Proportional is dependent upon the present error, Integral is dependent upon the accumulation of past error, and Derivative is the prediction of future error. The results of each of the controls are then fed into a weighted sum, which then adjusts the output of the circuit, u(t). This output is fed into a control device, its value is fed back into the circuit, and the process is allowed to actively stabilize the circuit’s output to reach and hold at the set point value. The block diagram below illustrates very simply the action of a PID circuit. One or more of the controls can be utilized in any servo circuit depending on system demand and requirement (i.e., P, I, PI, PD, or PID).
Through proper setting of the controls in a PID circuit, relatively quick response with minimal overshoot (passing the set point value) and ringing (oscillation about the set point value) can be achieved. Let’s take as an example a temperature servo, such as that for temperature stabilization of a laser diode. The PID circuit will ultimately servo the current to a Thermo Electric Cooler (TEC) (often times through control of the gate voltage on an FET). Under this example, the current is referred to as the Manipulated Variable (MV). A thermistor is used to monitor the temperature of the laser diode, and the voltage over the thermistor is used as the Process Variable (PV). The Set Point (SP) voltage is set to correspond to the desired temperature. The error signal, e(t), is then just the difference between the SP and PV. A PID controller will generate the error signal and then change the MV to reach the desired result. If, for instance, e(t) states that the laser diode is too hot, the circuit will allow more current to flow through the TEC (proportional control). Since proportional control is proportional to e(t), it may not cool the laser diode quickly enough. In that event, the circuit will further increase the amount of current through the TEC (integral control) by looking at the previous errors and adjusting the output in order to reach the desired value. As the SP is reached [e(t) approaches zero], the circuit will decrease the current through the TEC in anticipation of reaching the SP (derivative control).
Please note that a PID circuit will not guarantee optimal control. Improper setting of the PID controls can cause the circuit to oscillate significantly and lead to instability in control. It is up to the user to properly adjust the PID gains to ensure proper performance.
The output of the PID control circuit, u(t), is given as
From here we can define the control units through their mathematical definition and discuss each in a little more detail. Proportional control is proportional to the error signal; as such, it is a direct response to the error signal generated by the circuit:
Larger proportional gain results is larger changes in response to the error, and thus affects the speed at which the controller can respond to changes in the system. While a high proportional gain can cause a circuit to respond swiftly, too high a value can cause oscillations about the SP value. Too low a value and the circuit cannot efficiently respond to changes in the system.
Integral control goes a step further than proportional gain, as it is proportional to not just the magnitude of the error signal but also the duration of the error.
Integral control is highly effective at increasing the response time of a circuit along with eliminating the steady-state error associated with purely proportional control. In essence integral control sums over the previous error, which was not corrected, and then multiplies that error by Ki to produce the integral response. Thus, for even small sustained error, a large aggregated integral response can be realized. However, due to the fast response of integral control, high gain values can cause significant overshoot of the SP value and lead to oscillation and instability. Too low and the circuit will be significantly slower in responding to changes in the system.
Derivative control attempts to reduce the overshoot and ringing potential from proportional and integral control. It determines how quickly the circuit is changing over time (by looking at the derivative of the error signal) and multiplies it by Kd to produce the derivative response.
Unlike proportional and integral control, derivative control will slow the response of the circuit. In doing so, it is able to partially compensate for the overshoot as well as damp out any oscillations caused by integral and proportional control. High gain values cause the circuit to respond very slowly and can leave one susceptible to noise and high frequency oscillation (as the circuit becomes too slow to respond quickly). Too low and the circuit is prone to overshooting the SP value. However, in some cases overshooting the SP value by any significant amount must be avoided and thus a higher derivative gain (along with lower proportional gain) can be used. The chart below explains the effects of increasing the gain of any one of the parameters independently.
In general the gains of P, I, and D will need to be adjusted by the user in order to best servo the system. While there is not a static set of rules for what the values should be for any specific system, following the general procedures should help in tuning a circuit to match one’s system and environment. In general a PID circuit will typically overshoot the SP value slightly and then quickly damp out to reach the SP value.
Manual tuning of the gain settings is the simplest method for setting the PID controls. However, this procedure is done actively (the PID controller turned on and properly attached to the system) and requires some amount of experience to fully integrate. To tune your PID controller manually, first the integral and derivative gains are set to zero. Increase the proportional gain until you observe oscillation in the output. Your proportional gain should then be set to roughly half this value. After the proportional gain is set, increase the integral gain until any offset is corrected for on a time scale appropriate for your system. If you increase this gain too much, you will observe significant overshoot of the SP value and instability in the circuit. Once the integral gain is set, the derivative gain can then be increased. Derivative gain will reduce overshoot and damp the system quickly to the SP value. If you increase the derivative gain too much, you will see large overshoot (due to the circuit being too slow to respond). By playing with the gain settings, you can maximize the performance of your PID circuit, resulting in a circuit that quickly responds to changes in the system and effectively damps out oscillation about the SP value.
While manual tuning can be very effective at setting a PID circuit for your specific system, it does require some amount of experience and understanding of PID circuits and response. The Ziegler-Nichols method for PID tuning offers a bit more structured guide to setting PID values. Again, you’ll want to set the integral and derivative gain to zero. Increase the proportional gain until the circuit starts to oscillate. We will call this gain level Ku. The oscillation will have a period of Pu. Gains are for various control circuits are then given below in the chart.
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Custom Module for 14-Pin Butterfly Packages
Thorlabs OEM Manufacturing
In addition to manufacturing a wide variety of active optical devices, Thorlabs is equipped to deliver customized laser diode, superluminescent diode, and semiconductor optical amplifier modules in OEM quantities. For example, the module shown to the right provides temperature and current control for two superluminescent diodes (SLDs) from an SPI interface. Because this module is designed for standard 14-pin butterfly packages, it is easily adapted for combinations of other optical devices, such as a pigtailed semiconductor laser with an optical amplifier.
As a manufacturer of III-V semiconductor devices, MEMS-VCSEL lasers, quantum cascade lasers, lithium niobate optical modulators, and other devices, we are intimately familiar with the operating requirements of driving lasers and related components. Please visit this webpage for an overview of our laser manufacturing facility, or contact us directly to discuss your application's needs.
Laser Diode Controller Selection Guide
The tables below are designed to give a quick overview of the key specifications for our laser diode controllers and dual diode/temperature controllers. For more details and specifications, or to order a specific item, click on the appropriate item number below.